Urgent Help Needed!!

I am running a PSP with version 2.5 software installed..i want to run the Scumm Vm Emulator.

I have installed the emulator and it appears on my game memory card..howver, when i click on the flashing scumm icon it says data is corrupt??
I guess this means that i need to downgrade the software.

1. can it be downgraded?

2. will i ever get to play Scumm games on my psp?

2.5 can't be downgraded and homebrew can't be played that way on your version

search for GTA exploit

or go to fanjita's website... google it